EB-1: machines can die - structures get HP, Husks raze them, wounded base persists

Structures (Turret/Wall/Pylon) reuse the combat spine: authoring bakes Health(GhostField)+DamageEvent buffer+a Destructible tag (no HitRadius -> no friendly projectile fire; no EffectiveCharacterStats -> clamp-to-0). HealthApplyDamageSystem destroys a Destructible at 0 (occupancy auto-frees). EnemyAISystem fortress-targets the weighted-nearest of players+structures via the shared EnemyAIMath.PickWeightedNearest (StructureAggroWeight TuningConfig knob, <1 prefers structures, squared factor; snapshot above the early-return so an undefended base is razed). Persistence v3: per-structure HP threaded through 5 sites (SaveData/PendingStructure/scan-guarded/BaseRestore same-ECB born-correct/WorldLauncher via SaveApply.ToPending); SaveService floor-gate [2,3] loads old saves. Loss feedback: proximity-gated StructureFeedbackSystem; CombatFeedbackSystem suppressed for structures. Pre-code review caught the DamageEvent-buffer crash blocker + 8 majors; post-code review clean. See DR-032.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Authoring/Building/StructureAuthoring.cs

@@ -17,6 +17,8 @@ namespace ProjectM.Authoring
         [Tooltip("StructureType byte: 5 = Wall, 6 = Pylon (do NOT use 1-4: Turret + reserved M7 automation).")]
         public byte Kind = StructureType.Wall;
 
+        [Min(1f)] public float MaxHp = 150f;
+
         private class StructureBaker : Baker<StructureAuthoring>
         {
             public override void Bake(StructureAuthoring authoring)
@@ -29,6 +31,12 @@ namespace ProjectM.Authoring
                     NextTick = 0u,
                     LastProcessedTick = 0u,
                 });
+                // EB-1: Wall/Pylon are damageable + destructible AI targets (a wall soaks Husk strikes that would
+                // otherwise hit a turret). DamageEvent buffer MUST exist or an AI strike crashes at ECB playback.
+                // No HitRadius -> ProjectileDamageSystem ignores them (no friendly projectile fire).
+                AddComponent(entity, new Health { Current = authoring.MaxHp, Max = authoring.MaxHp });
+                AddBuffer<DamageEvent>(entity);
+                AddComponent<Destructible>(entity);
             }
         }
     }

Assets/_Project/Scripts/Authoring/Building/TurretAuthoring.cs

@@ -14,6 +14,7 @@ namespace ProjectM.Authoring
         [Min(1f)] public float Range = 10f;
         [Min(1)] public int CooldownTicks = 30;
         [Min(1f)] public float Damage = 12f;
+        [Min(1f)] public float MaxHp = 120f;
 
         private class TurretBaker : Baker<TurretAuthoring>
         {
@@ -33,6 +34,13 @@ namespace ProjectM.Authoring
                     CooldownTicks = authoring.CooldownTicks,
                     Damage = authoring.Damage,
                 });
+                // EB-1: structures are damageable + destructible (Husks push for them; HealthApplyDamageSystem
+                // destroys a Destructible at Health<=0). The DamageEvent buffer MUST exist on the archetype or an
+                // AI/turret strike crashes at ECB playback. NO HitRadius on purpose -> ProjectileDamageSystem (needs
+                // Health+HitRadius) ignores structures, so player shots never friendly-fire your own turret.
+                AddComponent(entity, new Health { Current = authoring.MaxHp, Max = authoring.MaxHp });
+                AddBuffer<DamageEvent>(entity);
+                AddComponent<Destructible>(entity);
             }
         }
     }

Assets/_Project/Scripts/Client/Debug/DebugOverlay.cs

@@ -104,6 +104,8 @@ namespace ProjectM.Client
                 TuningRow("Melee knock spd", TuningKnob.MeleeKnockbackSpeed, 1f, "0.0");
                 TuningRow("Melee finish x", TuningKnob.MeleeFinisherMult, 0.1f, "0.0");
                 TuningRow("Melee combo len", TuningKnob.MeleeComboLength, 1f, "0");
+                GUILayout.Space(4);
+                TuningRow("Struct aggro w", TuningKnob.StructureAggroWeight, 0.1f, "0.00"); // EB-1: <1 prefers structures
             }
 
             GUILayout.EndScrollView();

Assets/_Project/Scripts/Client/Presentation/CombatFeedbackSystem.cs

@@ -172,6 +172,7 @@ namespace ProjectM.Client
                 bool isEnemy = SystemAPI.HasComponent<EnemyTag>(entity);
                 uint windup = isEnemy && SystemAPI.HasComponent<AttackWindup>(entity) ? SystemAPI.GetComponent<AttackWindup>(entity).WindUpUntilTick : 0u;
                 bool isLocalPlayer = entity == _localPlayer;
+                bool isStructure = SystemAPI.HasComponent<PlacedStructure>(entity); // EB-1: suppress combat cues -> StructureFeedbackSystem
 
                 if (_cache.TryGetValue(entity, out var prev))
                 {
@@ -184,7 +185,7 @@ namespace ProjectM.Client
 
                     // Local hit feedback is SUPPRESSED while the local i-frame window is active: the server
                     // negates the hit; any transient Health dip is reconciliation flicker, not a real hit.
-                    if (cur < prev.Hp - 0.001f && !(isLocalPlayer && localIFrameActive && FeelConfig.DashHitSuppress))
+                    if (cur < prev.Hp - 0.001f && !isStructure && !(isLocalPlayer && localIFrameActive && FeelConfig.DashHitSuppress))
                     {
                         SpawnNumber(prev.Hp - cur, (Vector3)p, isLocalPlayer, cam);
                         Burst(_hitFx, cfg != null ? cfg.Hit : null, (Vector3)p + Vector3.up * 0.8f, FeelConfig.HitBurstCount);
@@ -202,7 +203,9 @@ namespace ProjectM.Client
                     }
 
                     // Player death (players don't despawn — they respawn; Husk death is handled on prune).
-                    if (!isEnemy && cur <= 0f && prev.Hp > 0f)
+                    // EB-1: structures (not EnemyTag) would otherwise fire the HUMAN player-death cue here; their
+                    // damage/death is routed entirely through StructureFeedbackSystem (gated by !isStructure).
+                    if (!isEnemy && !isStructure && cur <= 0f && prev.Hp > 0f)
                     {
                         Burst(_deathFx, PlayerDeathPrefab(cfg), (Vector3)p + Vector3.up * 0.5f, FeelConfig.DeathBurstCount);
                         PlayClip(_deathClip, (Vector3)p, 0.7f);

Assets/_Project/Scripts/Client/Presentation/StructureFeedbackSystem.cs

@@ -0,0 +1,216 @@
+using System.Collections.Generic;
+using ProjectM.Simulation;
+using Unity.Entities;
+using Unity.Mathematics;
+using Unity.NetCode;
+using Unity.Transforms;
+using UnityEngine;
+
+namespace ProjectM.Client
+{
+    /// <summary>
+    /// EB-1 — client-only WORLD JUICE for player-built structures taking damage + dying ("loses have weight"). A
+    /// managed <see cref="SystemBase"/> in <see cref="PresentationSystemGroup"/> that OBSERVES replicated state and
+    /// never mutates the sim: it edge-detects each structure ghost's [GhostField] <c>Health.Current</c> — a decrease
+    /// spawns a small amber chip (camera-SILENT so a siege's many hits never clamp the shake), and a destruction
+    /// (an HP&lt;=0 edge OR a despawn) spawns a LOUD red-orange burst + camera punch. A PROXIMITY GATE suppresses the
+    /// destruction burst unless the structure was near the local player, so the base->expedition RegionRelevancy
+    /// despawn (every base structure drops from this client at once) stays SILENT. De-duped: a structure fires its
+    /// death burst AT MOST once (the HP&lt;=0 edge sets DeathFired so the prune-cleanup skips it; the server destroys
+    /// a structure the same tick it hits 0, so the prune is usually the path that fires). CombatFeedbackSystem
+    /// suppresses structures, so this is the SOLE structure cue. Procedural particles + SFX (mirrors
+    /// WorldFeedbackSystem; self-contained). Never destroys a ghost (GhostDespawnSystem owns despawn); prunes the
+    /// cache EVERY frame (no <c>[RequireMatchingQueriesForUpdate]</c> — else a cache entry leaks per kill).
+    /// </summary>
+    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
+    [UpdateInGroup(typeof(PresentationSystemGroup))]
+    public partial class StructureFeedbackSystem : SystemBase
+    {
+        struct Cache { public float Hp; public float3 Pos; public bool DeathFired; }
+
+        readonly Dictionary<Entity, Cache> _cache = new();
+        readonly HashSet<Entity> _seen = new();
+        readonly List<Entity> _stale = new();
+
+        Transform _fxRoot;
+        ParticleSystem _chipFx;
+        ParticleSystem _deathFx;
+        AudioClip _chipClip;
+        AudioClip _deathClip;
+
+        protected override void OnCreate()
+        {
+            _chipClip = MakeClip("struct_chip", 700f, 500f, 0.05f, 0.30f);
+            _deathClip = MakeClip("struct_death", 220f, 60f, 0.35f, 0.55f);
+        }
+
+        protected override void OnStartRunning()
+        {
+            if (_fxRoot != null) return;
+            _fxRoot = new GameObject("~StructureFeedbackFX").transform;
+            var mat = MakeParticleMaterial();
+            _chipFx = MakeBurst("StructChips", mat, StructureFeelConfig.DamageTint, 0.12f, 5f, 0.30f, 256);
+            _deathFx = MakeBurst("StructDeath", mat, StructureFeelConfig.DeathTint, 0.20f, 8f, 0.55f, 512);
+        }
+
+        protected override void OnDestroy()
+        {
+            if (_fxRoot != null) Object.Destroy(_fxRoot.gameObject);
+        }
+
+        protected override void OnUpdate()
+        {
+            if (!StructureFeelConfig.Enabled) { _cache.Clear(); return; }
+
+            EntityManager.CompleteDependencyBeforeRO<Health>();
+            EntityManager.CompleteDependencyBeforeRO<PlacedStructure>();
+            EntityManager.CompleteDependencyBeforeRO<LocalTransform>();
+
+            bool haveLocal = false;
+            float3 localPos = default;
+            foreach (var xf in SystemAPI.Query<RefRO<LocalTransform>>().WithAll<GhostOwnerIsLocal, PlayerTag>())
+            {
+                localPos = xf.ValueRO.Position;
+                haveLocal = true;
+            }
+            float rangeSq = StructureFeelConfig.ProximityRange * StructureFeelConfig.ProximityRange;
+
+            _seen.Clear();
+            foreach (var (health, xf, e) in
+                     SystemAPI.Query<RefRO<Health>, RefRO<LocalTransform>>().WithAll<PlacedStructure>().WithEntityAccess())
+            {
+                _seen.Add(e);
+                float cur = health.ValueRO.Current;
+                float3 pos = xf.ValueRO.Position;
+                bool nearby = haveLocal && math.distancesq(pos, localPos) <= rangeSq;
+
+                if (_cache.TryGetValue(e, out var prev))
+                {
+                    if (cur <= 0f && prev.Hp > 0f && !prev.DeathFired)
+                    {
+                        if (nearby) FireDeath(pos);
+                        _cache[e] = new Cache { Hp = cur, Pos = pos, DeathFired = true };
+                        continue;
+                    }
+                    if (cur < prev.Hp - 0.001f && cur > 0f && nearby)
+                    {
+                        EmitTinted(_chipFx, (Vector3)pos + Vector3.up * 0.7f, StructureFeelConfig.ChipBurstCount, StructureFeelConfig.DamageTint);
+                        PlayClip(_chipClip, (Vector3)pos, StructureFeelConfig.ChipSfxVolume);
+                    }
+                }
+                _cache[e] = new Cache { Hp = cur, Pos = pos, DeathFired = _cache.TryGetValue(e, out var c2) && c2.DeathFired };
+            }
+
+            // Prune: a despawn = destroyed (or a region-transit drop). Proximity-gated so the +1000 base->expedition
+            // despawn stays silent; de-duped against an HP<=0 edge that already fired this structure's death.
+            if (_cache.Count != _seen.Count)
+            {
+                _stale.Clear();
+                foreach (var kv in _cache)
+                    if (!_seen.Contains(kv.Key)) _stale.Add(kv.Key);
+                for (int i = 0; i < _stale.Count; i++)
+                {
+                    var c = _cache[_stale[i]];
+                    if (!c.DeathFired && haveLocal && math.distancesq(c.Pos, localPos) <= rangeSq)
+                        FireDeath(c.Pos);
+                    _cache.Remove(_stale[i]);
+                }
+            }
+        }
+
+        void FireDeath(float3 pos)
+        {
+            EmitTinted(_deathFx, (Vector3)pos + Vector3.up * 0.6f, StructureFeelConfig.DeathBurstCount, StructureFeelConfig.DeathTint);
+            PlayClip(_deathClip, (Vector3)pos, StructureFeelConfig.DeathSfxVolume);
+            PrototypeCameraRig.PunchFov(StructureFeelConfig.DeathFovKick, 110f);
+            PrototypeCameraRig.AddShake(StructureFeelConfig.DeathShake);
+        }
+
+        // ---- procedural particles + SFX (mirrors WorldFeedbackSystem; self-contained) ----
+
+        static void EmitTinted(ParticleSystem ps, Vector3 pos, int count, Color tint)
+        {
+            if (ps == null) return;
+            var main = ps.main;
+            main.startColor = tint;
+            ps.transform.position = pos;
+            ps.Emit(count);
+        }
+
+        static Material MakeParticleMaterial()
+        {
+            Shader sh = Shader.Find("Sprites/Default");
+            if (sh == null) sh = Shader.Find("Universal Render Pipeline/Particles/Unlit");
+            if (sh == null) sh = Shader.Find("Unlit/Color");
+            return new Material(sh) { name = "StructureFeedbackParticle" };
+        }
+
+        ParticleSystem MakeBurst(string name, Material mat, Color color, float size, float speed, float life, int max)
+        {
+            var go = new GameObject(name);
+            go.transform.SetParent(_fxRoot, false);
+            var ps = go.AddComponent<ParticleSystem>();
+
+            var main = ps.main;
+            main.loop = false;
+            main.playOnAwake = false;
+            main.startLifetime = life;
+            main.startSpeed = speed;
+            main.startSize = size;
+            main.startColor = color;
+            main.maxParticles = max;
+            main.gravityModifier = 0.3f;
+            main.simulationSpace = ParticleSystemSimulationSpace.World;
+
+            var emission = ps.emission;
+            emission.enabled = false; // manual Emit(count)
+
+            var shape = ps.shape;
+            shape.enabled = true;
+            shape.shapeType = ParticleSystemShapeType.Sphere;
+            shape.radius = 0.18f;
+
+            var colOverLife = ps.colorOverLifetime;
+            colOverLife.enabled = true;
+            var grad = new Gradient();
+            grad.SetKeys(
+                new[] { new GradientColorKey(Color.white, 0f), new GradientColorKey(Color.white, 1f) },
+                new[] { new GradientAlphaKey(1f, 0f), new GradientAlphaKey(0f, 1f) });
+            colOverLife.color = new ParticleSystem.MinMaxGradient(grad);
+
+            var sizeOverLife = ps.sizeOverLifetime;
+            sizeOverLife.enabled = true;
+            sizeOverLife.size = new ParticleSystem.MinMaxCurve(1f, AnimationCurve.Linear(0f, 1f, 1f, 0.15f));
+
+            var renderer = ps.GetComponent<ParticleSystemRenderer>();
+            renderer.material = mat;
+            renderer.renderMode = ParticleSystemRenderMode.Billboard;
+            return ps;
+        }
+
+        static AudioClip MakeClip(string name, float f0, float f1, float dur, float vol)
+        {
+            const int rate = 44100;
+            int len = Mathf.Max(16, (int)(dur * rate));
+            var clip = AudioClip.Create(name, len, 1, rate, false);
+            var data = new float[len];
+            float phase = 0f;
+            for (int i = 0; i < len; i++)
+            {
+                float t = i / (float)len;
+                float env = Mathf.Exp(-5f * t);
+                float freq = Mathf.Lerp(f0, f1, t);
+                phase += 2f * Mathf.PI * freq / rate;
+                data[i] = Mathf.Sin(phase) * env * vol;
+            }
+            clip.SetData(data, 0);
+            return clip;
+        }
+
+        static void PlayClip(AudioClip clip, Vector3 pos, float vol)
+        {
+            if (clip == null) return;
+            AudioSource.PlayClipAtPoint(clip, pos, vol * GameVolume.Sfx);
+        }
+    }
+}

Assets/_Project/Scripts/Client/Presentation/StructureFeedbackSystem.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 61153a58a80eb0542bbdc62085cce81b

Assets/_Project/Scripts/Client/Presentation/StructureFeelConfig.cs

@@ -0,0 +1,47 @@
+using UnityEngine;
+
+namespace ProjectM.Client
+{
+    /// <summary>
+    /// EB-1 — static live-tunable knobs for <see cref="StructureFeedbackSystem"/> (structure damage chips +
+    /// destruction bursts). A presentation-only bridge (mirrors <c>WorldFeelConfig</c>); reset on play-enter via
+    /// <see cref="RuntimeInitializeOnLoadMethod"/> so poked values never leak across fast-enter-playmode sessions.
+    /// Read only on the main thread by the managed feedback system, never from Burst.
+    /// </summary>
+    public static class StructureFeelConfig
+    {
+        public static bool Enabled = true;
+
+        /// <summary>A despawn farther than this from the local player does NOT fire a death burst — so the
+        /// base->expedition RegionRelevancy despawn (all base structures drop at once) stays silent.</summary>
+        public static float ProximityRange = 45f;
+
+        public static int ChipBurstCount = 8;
+        public static int DeathBurstCount = 40;
+        public static float ChipSfxVolume = 0.25f;
+        public static float DeathSfxVolume = 0.6f;
+
+        // A LOUD, low-frequency punch is reserved for a structure DEATH only; per-chip feedback is camera-silent so
+        // a wave of hits never sustains a nauseating shake (AddShake clamps cumulatively, PunchFov takes a max).
+        public static float DeathFovKick = 5.5f;
+        public static float DeathShake = 0.35f;
+
+        public static Color DamageTint = new Color(2.4f, 1.4f, 0.4f);  // amber HDR spark on a hit
+        public static Color DeathTint = new Color(3.0f, 0.7f, 0.25f);  // red-orange HDR loss burst
+
+        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
+        static void ResetDefaults()
+        {
+            Enabled = true;
+            ProximityRange = 45f;
+            ChipBurstCount = 8;
+            DeathBurstCount = 40;
+            ChipSfxVolume = 0.25f;
+            DeathSfxVolume = 0.6f;
+            DeathFovKick = 5.5f;
+            DeathShake = 0.35f;
+            DamageTint = new Color(2.4f, 1.4f, 0.4f);
+            DeathTint = new Color(3.0f, 0.7f, 0.25f);
+        }
+    }
+}

Assets/_Project/Scripts/Client/Presentation/StructureFeelConfig.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: c868d6648bec9fd4199c44fcf8330326

Assets/_Project/Scripts/Client/UI/WorldLauncher.cs

@@ -120,11 +120,7 @@ namespace ProjectM.Client
                 var se = em.CreateEntity();
                 var sbuf = em.AddBuffer<PendingStructure>(se);
                 foreach (var s in data.Structures)
-                    sbuf.Add(new PendingStructure
-                    {
-                        Type = s.Type, CellX = s.CellX, CellZ = s.CellZ, Direction = s.Direction,
-                        RemainingTicks = s.RemainingTicks, ConveyorResId = s.ConveyorResId, ConveyorCount = s.ConveyorCount,
-                    });
+                    sbuf.Add(SaveApply.ToPending(s)); // EB-1: pure mapping (unit-tested, incl. the wounded HP)
                 var iobuf = em.AddBuffer<PendingStructureIo>(se);
                 if (data.StructureIo != null)
                     foreach (var io in data.StructureIo)

Assets/_Project/Scripts/Server/Automation/BaseRestoreSystem.cs

@@ -25,12 +25,14 @@ namespace ProjectM.Server
     {
         ComponentLookup<LocalTransform> m_TransformLookup;
         ComponentLookup<Conveyor> m_ConveyorLookup;
+        ComponentLookup<Health> m_HealthLookup;
 
         [BurstCompile]
         public void OnCreate(ref SystemState state)
         {
             m_TransformLookup = state.GetComponentLookup<LocalTransform>(isReadOnly: true);
             m_ConveyorLookup = state.GetComponentLookup<Conveyor>(isReadOnly: true);
+            m_HealthLookup = state.GetComponentLookup<Health>(isReadOnly: true);
             state.RequireForUpdate<StructureCatalog>();
             state.RequireForUpdate<BaseAnchor>();
             state.RequireForUpdate<NetworkTime>();
@@ -47,6 +49,7 @@ namespace ProjectM.Server
 
             m_TransformLookup.Update(ref state);
             m_ConveyorLookup.Update(ref state);
+            m_HealthLookup.Update(ref state);
 
             var anchor = SystemAPI.GetSingleton<BaseAnchor>();
             var catalog = SystemAPI.GetBuffer<StructureCatalogEntry>(SystemAPI.GetSingletonEntity<StructureCatalog>());
@@ -81,6 +84,14 @@ namespace ProjectM.Server
                         NextTick = ProductionMath.RestoreNextTick(now, p.RemainingTicks),
                         LastProcessedTick = TickUtil.NonZero(now),
                     });
+                    // EB-1: restore the wounded HP born-correct in the SAME ecb as Instantiate (Health.Current is a
+                    // [GhostField]; a deferred set would leak baked Max to clients for one snapshot). Max + the
+                    // 0->full fallback come from the BAKED prefab, never the save. Automation machines lack Health.
+                    if (m_HealthLookup.HasComponent(prefab))
+                    {
+                        var hm = m_HealthLookup[prefab];
+                        ecb.SetComponent(structure, new Health { Current = p.HP > 0f ? p.HP : hm.Max, Max = hm.Max });
+                    }
                     ecb.AddComponent(structure, new RegionTag { Region = RegionId.Base });
                     ecb.AddComponent<RuntimePlacedTag>(structure);
 

Assets/_Project/Scripts/Server/Combat/EnemyAISystem.cs

@@ -51,10 +51,28 @@ namespace ProjectM.Server
                 playerPositions.Add(xform.ValueRO.Position);
             }
 
-            if (playerEntities.Length == 0)
+            // EB-1 fortress aggro: also snapshot live structures (Turret/Wall/Pylon carry Health; automation
+            // machines lack it so the query excludes them). Snapshot ABOVE the early-return so Husks keep razing
+            // the base even with every player dead/away (the locked 'push for structures' fork).
+            var structureEntities = new NativeList<Entity>(Allocator.Temp);
+            var structurePositions = new NativeList<float3>(Allocator.Temp);
+            foreach (var (sx, sh, se) in
+                     SystemAPI.Query<RefRO<LocalTransform>, RefRO<Health>>()
+                         .WithAll<PlacedStructure>()
+                         .WithEntityAccess())
+            {
+                if (sh.ValueRO.Current <= 0f)
+                    continue; // skip a structure already at 0 (pending destroy this tick)
+                structureEntities.Add(se);
+                structurePositions.Add(sx.ValueRO.Position);
+            }
+
+            if (playerEntities.Length == 0 && structureEntities.Length == 0)
             {
                 playerEntities.Dispose();
                 playerPositions.Dispose();
+                structureEntities.Dispose();
+                structurePositions.Dispose();
                 return;
             }
 
@@ -63,6 +81,7 @@ namespace ProjectM.Server
             uint now = serverTick.TickIndexForValidTick;
             // Live feel knobs (MC-0): one read, guarded at use. Server-only — clients never simulate enemies.
             var tune = SystemAPI.TryGetSingleton<TuningConfig>(out var tcfg) ? tcfg : TuningConfig.Defaults();
+            float structAggro = math.max(0f, tune.StructureAggroWeight);
             var ecb = new EntityCommandBuffer(Allocator.Temp);
             bool havePhysics = SystemAPI.TryGetSingleton<PhysicsWorldSingleton>(out var physics);
             uint envMask = SystemAPI.TryGetSingleton<WorldCollisionConfig>(out var worldCol) ? worldCol.EnvironmentMask : 0u;
@@ -95,21 +114,13 @@ namespace ProjectM.Server
                     knockback.ValueRW.UntilTick = 0; // window elapsed
                 }
 
-                // Nearest living player (planar XZ).
-                int best = -1;
-                float bestSq = float.MaxValue;
-                for (int i = 0; i < playerPositions.Length; i++)
-                {
-                    float2 d = playerPositions[i].xz - pos.xz;
-                    float sq = math.lengthsq(d);
-                    if (sq < bestSq)
-                    {
-                        bestSq = sq;
-                        best = i;
-                    }
-                }
-
-                float3 targetPos = playerPositions[best];
+                // EB-1 fortress aggro: nearest of players (weight 1) + structures (StructureAggroWeight) — a wall/
+                // turret is the preferred target unless a player is in the way (closer after weighting).
+                EnemyAIMath.PickWeightedNearest(pos, playerPositions, structurePositions, structAggro, out bool tgtIsStruct, out int tgtIdx);
+                if (tgtIdx < 0)
+                    continue; // no target (covered by the early-return, but stay safe)
+                Entity targetEntity = tgtIsStruct ? structureEntities[tgtIdx] : playerEntities[tgtIdx];
+                float3 targetPos = tgtIsStruct ? structurePositions[tgtIdx] : playerPositions[tgtIdx];
 
                 // Seek: stop just inside strike range so the Husk holds position to attack.
                 float stopDistance = stats.ValueRO.AttackRange * 0.9f;
@@ -143,7 +154,7 @@ namespace ProjectM.Server
                         var windTick = new NetworkTick(windRaw);
                         if (!(windTick.IsValid && windTick.IsNewerThan(serverTick)))
                         {
-                            ecb.AppendToBuffer(playerEntities[best], new DamageEvent
+                            ecb.AppendToBuffer(targetEntity, new DamageEvent
                             {
                                 Amount = stats.ValueRO.AttackDamage,
                                 SourceNetworkId = -1, // environment / Husk, not a player
@@ -207,15 +218,12 @@ namespace ProjectM.Server
                     knockback.ValueRW.UntilTick = 0;
                 }
 
-                // Nearest living player (reuse the snapshot taken above).
-                int cbest = -1; float cbestSq = float.MaxValue;
-                for (int i = 0; i < playerPositions.Length; i++)
-                {
-                    float2 dd = playerPositions[i].xz - pos.xz;
-                    float sq = math.lengthsq(dd);
-                    if (sq < cbestSq) { cbestSq = sq; cbest = i; }
-                }
-                float3 cTargetPos = playerPositions[cbest];
+                // EB-1 fortress aggro: same weighted target selection as the Grunt pass (shared helper).
+                EnemyAIMath.PickWeightedNearest(pos, playerPositions, structurePositions, structAggro, out bool cIsStruct, out int cIdx);
+                if (cIdx < 0)
+                    continue;
+                Entity cTargetEntity = cIsStruct ? structureEntities[cIdx] : playerEntities[cIdx];
+                float3 cTargetPos = cIsStruct ? structurePositions[cIdx] : playerPositions[cIdx];
 
                 // 2. Lunge active: travel the locked direction; damage on contact, or stagger on a wall-stop whiff.
                 var lg = lunge.ValueRO;
@@ -233,7 +241,7 @@ namespace ProjectM.Server
 
                         if (EnemyAIMath.InAttackRange(moved, cTargetPos, stats.ValueRO.AttackRange))
                         {
-                            ecb.AppendToBuffer(playerEntities[cbest], new DamageEvent
+                            ecb.AppendToBuffer(cTargetEntity, new DamageEvent
                             {
                                 Amount = stats.ValueRO.AttackDamage,
                                 SourceNetworkId = -1,
@@ -312,6 +320,8 @@ namespace ProjectM.Server
             ecb.Dispose();
             playerEntities.Dispose();
             playerPositions.Dispose();
+            structureEntities.Dispose();
+            structurePositions.Dispose();
         }
 
         // Swept collide-and-slide for server-authoritative Husk movement: sphere-cast the intended step against

Assets/_Project/Scripts/Server/Combat/HealthApplyDamageSystem.cs

@@ -132,8 +132,11 @@ namespace ProjectM.Server
 
                 health.ValueRW.Current = newHp;
 
-                // Server-authoritative death: training dummies despawn; player death is deferred (clamp only).
-                if (health.ValueRO.Current <= 0f && (SystemAPI.HasComponent<TrainingDummyTag>(entity) || SystemAPI.HasComponent<EnemyTag>(entity)))
+                // Server-authoritative death: training dummies + enemies + EB-1 Destructible structures despawn;
+                // player death is deferred (clamp only). A structure carries NO EffectiveCharacterStats, so it took
+                // the math.max(0,..) branch above and CAN reach 0 — never give a structure stats (it would clamp to
+                // a non-zero floor and become immortal).
+                if (health.ValueRO.Current <= 0f && (SystemAPI.HasComponent<TrainingDummyTag>(entity) || SystemAPI.HasComponent<EnemyTag>(entity) || SystemAPI.HasComponent<Destructible>(entity)))
                     ecb.DestroyEntity(entity);
             }
             if ((negatedThisTick != 0u || punishesThisTick != 0u) && SystemAPI.HasSingleton<DevTelemetry>())

Assets/_Project/Scripts/Simulation/Combat/Destructible.cs

@@ -0,0 +1,14 @@
+using Unity.Entities;
+
+namespace ProjectM.Simulation
+{
+    /// <summary>
+    /// EB-1 — opt-in marker for an entity that <see cref="ProjectM.Server.HealthApplyDamageSystem"/> DESTROYS when
+    /// its <see cref="Health"/> hits 0 (alongside <c>TrainingDummyTag</c>/<c>EnemyTag</c>). Baked ONLY on the
+    /// player-built structure ghosts (Turret/Wall/Pylon) so "machines can die". DELIBERATELY a distinct tag rather
+    /// than gating on bare <see cref="PlacedStructure"/>: that identity is SHARED by the reserved M7 automation
+    /// machines (Harvester/Fabricator/Conveyor) whose teardown would silently drop in-flight conveyor cargo — the
+    /// tag lets each destructible opt in explicitly (zero-size, ghost-hash-neutral). See [[DR-031]] follow-on EB-1.
+    /// </summary>
+    public struct Destructible : IComponentData { }
+}

Assets/_Project/Scripts/Simulation/Combat/Destructible.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: a0efc019048795541ba13795d724f331

Assets/_Project/Scripts/Simulation/Combat/EnemyAIMath.cs

@@ -1,3 +1,4 @@
+using Unity.Collections;
 using Unity.Mathematics;
 
 namespace ProjectM.Simulation
@@ -68,5 +69,31 @@ namespace ProjectM.Simulation
             math.sincos(angle, out float s, out float c);
             return center + new float3(c * radius, 0f, s * radius);
         }
+        /// <summary>
+        /// EB-1 fortress aggro: pick a Husk's target as the weighted-nearest of the living players (weight 1) and
+        /// the live structures (a SQUARED <paramref name="structureWeight"/> applied to structure distance, so &lt;1
+        /// makes structures preferred while a sufficiently-closer player 'in the way' still wins). Planar XZ,
+        /// deterministic (no RNG/wall-clock). Sets <paramref name="index"/> = -1 when there are no targets. Pure so
+        /// both the Grunt and Charger passes select IDENTICALLY and it is EditMode-unit-testable.
+        /// </summary>
+        public static void PickWeightedNearest(float3 from, NativeList<float3> playerPositions,
+            NativeList<float3> structurePositions, float structureWeight, out bool isStructure, out int index)
+        {
+            isStructure = false;
+            index = -1;
+            float bestSq = float.MaxValue;
+            for (int i = 0; i < playerPositions.Length; i++)
+            {
+                float sq = math.lengthsq(playerPositions[i].xz - from.xz);
+                if (sq < bestSq) { bestSq = sq; index = i; isStructure = false; }
+            }
+            float w = math.max(0f, structureWeight);
+            float wsq = w * w; // applied to SQUARED distance so the weight scales true distance
+            for (int i = 0; i < structurePositions.Length; i++)
+            {
+                float sq = math.lengthsq(structurePositions[i].xz - from.xz) * wsq;
+                if (sq < bestSq) { bestSq = sq; index = i; isStructure = true; }
+            }
+        }
     }
 }

Assets/_Project/Scripts/Simulation/Debug/TuningConfig.cs

@@ -46,6 +46,10 @@ namespace ProjectM.Simulation
         public float MeleeFinisherMult;
         public float MeleeComboLength;
 
+        // EB-1 fortress aggro: a <1 multiplier on a Husk's SQUARED distance to a structure (so structures are
+        // preferred targets); a closer player 'in the way' still wins. Read server-side by EnemyAISystem.
+        public float StructureAggroWeight;
+
         /// <summary>The baked feel defaults == the pre-MC-0 consts. Single source of truth for the fallback path.</summary>
         public static TuningConfig Defaults() => new TuningConfig
         {
@@ -68,6 +72,7 @@ namespace ProjectM.Simulation
             MeleeKnockbackSpeed = 6f,
             MeleeFinisherMult = 1.8f,            // finisher (last hit) scales dmg/range/recover/knockback
             MeleeComboLength = 3f,               // light, light, finisher
+            StructureAggroWeight = 0.7f,           // EB-1: <1 prefers structures (fortress aggro); live-tunable
         };
 
         /// <summary>Clamp a knob to its safe floor: tick knobs &gt;= 1, value knobs &gt;= 0. Used by every write path
@@ -86,6 +91,7 @@ namespace ProjectM.Simulation
                 case TuningKnob.MeleeSwingMoveScale:
                 case TuningKnob.MeleeKnockbackSpeed:
                 case TuningKnob.MeleeFinisherMult:
+                case TuningKnob.StructureAggroWeight:
                     return math.max(0f, value);
                 // tick knobs: >= 1 (a 0 tick count is degenerate; a 0 i-frame window divides-by-zero in DashSystem)
                 default:
@@ -118,6 +124,7 @@ namespace ProjectM.Simulation
                 case TuningKnob.MeleeKnockbackSpeed: c.MeleeKnockbackSpeed = value; break;
                 case TuningKnob.MeleeFinisherMult: c.MeleeFinisherMult = value; break;
                 case TuningKnob.MeleeComboLength: c.MeleeComboLength = value; break;
+                case TuningKnob.StructureAggroWeight: c.StructureAggroWeight = value; break;
                 // unknown index -> no-op (matches the no-default switch convention in DebugCommandReceiveSystem)
             }
         }
@@ -146,6 +153,7 @@ namespace ProjectM.Simulation
                 case TuningKnob.MeleeKnockbackSpeed: return c.MeleeKnockbackSpeed;
                 case TuningKnob.MeleeFinisherMult: return c.MeleeFinisherMult;
                 case TuningKnob.MeleeComboLength: return c.MeleeComboLength;
+                case TuningKnob.StructureAggroWeight: return c.StructureAggroWeight;
                 default: return 0f;
             }
         }
@@ -172,6 +180,7 @@ namespace ProjectM.Simulation
             MeleeKnockbackSpeed = c.MeleeKnockbackSpeed,
             MeleeFinisherMult = c.MeleeFinisherMult,
             MeleeComboLength = c.MeleeComboLength,
+            StructureAggroWeight = c.StructureAggroWeight,
         };
 
         /// <summary>Reconstruct the full config from a wire snapshot (FULL state, not a delta).</summary>
@@ -196,6 +205,7 @@ namespace ProjectM.Simulation
             MeleeKnockbackSpeed = r.MeleeKnockbackSpeed,
             MeleeFinisherMult = r.MeleeFinisherMult,
             MeleeComboLength = r.MeleeComboLength,
+            StructureAggroWeight = r.StructureAggroWeight,
         };
     }
 
@@ -221,9 +231,10 @@ namespace ProjectM.Simulation
         public const byte MeleeKnockbackSpeed = 16;
         public const byte MeleeFinisherMult = 17;
         public const byte MeleeComboLength = 18;
+        public const byte StructureAggroWeight = 19;
 
         /// <summary>Knob count (overlay iteration bound).</summary>
-        public const byte Count = 19;
+        public const byte Count = 20;
     }
 
     /// <summary>
@@ -253,5 +264,6 @@ namespace ProjectM.Simulation
         public float MeleeKnockbackSpeed;
         public float MeleeFinisherMult;
         public float MeleeComboLength;
+        public float StructureAggroWeight;
     }
 }

Assets/_Project/Scripts/Simulation/Persistence/SaveApply.cs

@@ -15,5 +15,20 @@ namespace ProjectM.Simulation
             for (int i = 0; i < src.Length; i++)
                 dest.Add(new StorageEntry { ItemId = src[i].ItemId, Count = src[i].Count });
         }
+
+        /// <summary>EB-1: map a serialized <see cref="StructureSave"/> to the staged <see cref="PendingStructure"/>
+        /// (the menu->ServerWorld copy in WorldLauncher). Pure so the field-for-field copy — including the
+        /// easy-to-miss HP — is unit-tested; an omitted field here silently restores every structure at full HP.</summary>
+        public static PendingStructure ToPending(in StructureSave s) => new PendingStructure
+        {
+            Type = s.Type,
+            CellX = s.CellX,
+            CellZ = s.CellZ,
+            Direction = s.Direction,
+            RemainingTicks = s.RemainingTicks,
+            ConveyorResId = s.ConveyorResId,
+            ConveyorCount = s.ConveyorCount,
+            HP = s.HP,
+        };
     }
 }

Assets/_Project/Scripts/Simulation/Persistence/SaveComponents.cs

@@ -37,6 +37,7 @@ namespace ProjectM.Simulation
         public uint RemainingTicks;
         public byte ConveyorResId;
         public int ConveyorCount;
+        public float HP; // EB-1: staged hit points (BaseRestoreSystem restores 0 -> baked Max)
     }
 
     /// <summary>One staged machine I/O row (M7), joined to the <see cref="PendingStructure"/> buffer by index.

Assets/_Project/Scripts/Simulation/Persistence/SaveData.cs

@@ -25,6 +25,7 @@ namespace ProjectM.Simulation
         public uint RemainingTicks;  // production/cooldown ticks left at save time
         public byte ConveyorResId;   // in-flight conveyor item resource (0 = none)
         public int ConveyorCount;
+        public float HP;             // EB-1: hit points at save time (0 from a pre-v3 save -> restored to baked Max)
     }
 
     /// <summary>
@@ -50,7 +51,10 @@ namespace ProjectM.Simulation
     [Serializable]
     public class SaveData
     {
-        public const int CurrentVersion = 2;
+        public const int CurrentVersion = 3; // EB-1: v3 adds StructureSave.HP
+
+        /// <summary>Oldest save schema the loader accepts (additive); a v2 save loads with structures at full HP.</summary>
+        public const int MinLoadableVersion = 2;
 
         public int Version = CurrentVersion;
         public int GoalCharge;

Assets/_Project/Scripts/Simulation/Persistence/SaveService.cs

@@ -23,7 +23,9 @@ namespace ProjectM.Simulation
             {
                 if (!File.Exists(FilePath)) return null;
                 var data = JsonUtility.FromJson<SaveData>(File.ReadAllText(FilePath));
-                if (data == null || data.Version != SaveData.CurrentVersion) return null;
+                // EB-1: additive floor [MinLoadableVersion, CurrentVersion] so OLD v2 saves still load (a missing HP
+                // field 0-defaults and the restore guard maps 0 -> baked Max); v0/v1 garbage is still rejected.
+                if (data == null || data.Version < SaveData.MinLoadableVersion || data.Version > SaveData.CurrentVersion) return null;
                 data.Ledger ??= Array.Empty<LedgerRow>();
                 return data;
             }

Assets/_Project/Scripts/Simulation/Persistence/SaveStructureScan.cs

@@ -35,6 +35,8 @@ namespace ProjectM.Simulation
                     CellX = ps.Cell.x,
                     CellZ = ps.Cell.y,
                     RemainingTicks = ProductionMath.RemainingTicks(ps.NextTick, nowTick),
+                    // EB-1: guarded so automation machines (no Health) don't crash the autosave path (no try/catch).
+                    HP = em.HasComponent<Health>(e) ? em.GetComponentData<Health>(e).Current : 0f,
                 };
 
                 if (em.HasComponent<Conveyor>(e))